Please translate the following sentence into English according to the style of SCI journals升温阶段火灾导致隧道内部混凝土受热膨胀隧道外部混凝土受拉开裂；降温阶段隧道内部因降温开裂。在这种内外交替开裂的模式下沉管隧道容易形成贯穿裂缝。

During the heating phase, the concrete inside the tunnel expands due to the fire, while the concrete outside the tunnel undergoes tensile cracking. During the cooling phase, the inside of the tunnel undergoes cracking due to the decrease in temperature. In this pattern of alternating internal and external cracking, the immersed tunnel is susceptible to the formation of penetrating cracks.